Tuesday's deadly bombing in Maiduguri appears to be the continuation of a string of fatal explosions around Nigeria and allegedly linked to the militant Islamist sect.

ByHaruna Umar and Michelle Faul, Associated PressJuly 1, 2014

People gather at the scene of a car bomb explosion, at the central market, in Maiduguri, Nigeria, Tuesday, July 1, 2014. A car bomb exploded in a market in Nigeria’s northeastern city of Maiduguri on Tuesday morning, and dozens of people are feared dead, witnesses said.

Maiduguri, Nigeria — A car bomb exploded Tuesday in a market in Maiduguri, the northeast Nigerian city that is the birthplace of Boko Haram Islamic extremists, reducing stalls, goods and vehicles to piles of trash. Dozens of people are feared dead, witnesses said.

They blamed Boko Haram extremists who are accused of a series of recent bomb attacks in the West African nation.

Tuesday's explosives were hidden under a load of charcoal in a pickup van, according to witnesses who spoke on condition of anonymity for fear of reprisals.

Stalls and goods were reduced to debris as were the burned-out hulks of five cars and some tricycle taxis set ablaze by the explosion.

Yobe said security forces cordoned off the area but had a hard time keeping people out, though they warned there could be secondary explosions timed to target rescue efforts.

Witnesses said they saw about 50 bodies. They said the toll may be worse but fewer than normal traders and customers were around because most people stay up late to eat during Ramadan, the Muslim month of fasting from sunrise to sunset.

A security official at the scene confirmed the blast, saying many casualties are feared. He spoke on condition of anonymity because he was not permitted to speak to the press.

Explosions last week targeted the biggest shopping mall in Abuja, Nigeria's central capital, killing 24 people; a medical college in northern Kano city, killing at least eight; and a hotel brothel in northeast Bauchi city that killed 10. It was the third bomb blast in as many months in Abuja, and the second in two months in Kano. In May, twin car bombs at a marketplace also left more than 130 dead in central Jos city and killed at least 14 people at a World Cup viewing site in Damaturu, another town in the northeast.

Maiduguri, a city of more than 1 million people, has suffered many attacks. In March, twin car bombs killed more than 50 people at a late-night market where people were watching a football match on a big screen.

Boko Haram has attracted international attention and condemnation since its April abduction of more than 200 schoolgirls from a northeastern town.

Nigeria's military announced Monday night that it had busted a terrorist intelligence cell and arrested a businessman who "participated actively" in the mass abduction that caused outrage around the world.

It was unclear if the first arrest of a suspect in the kidnappings could help in rescuing at least 219 girls who remain captive. Boko Haram is threatening to sell the girls into marriage and slavery if Nigeria's government does not exchange them for detained insurgents.

Defense Ministry spokesman Maj. Gen. Chris Olukolade said in a statement that businessman Babuji Ya'ari belonged to a vigilante group fighting Boko Haram and used that membership as cover "while remaining an active terrorist."

He said information yielded by Ya'ari's detention had led to the arrests of two women — one who worked as a spy and arms procurer and another described as a paymaster.

Boko Haram has adopted a two-pronged strategy this year of bombings in urban areas and scorched-earth attacks in northeastern villages where people are gunned down and their homes burned.

On Sunday, suspected extremists sprayed gunfire on worshippers in four churches in a northeastern village and torched the buildings. At least 30 people were reported killed there.

The extremists have been attacking with more frequency and deadliness in recent months.

Nigeria's President Goodluck Jonathan on Monday condemned the recent attacks. A statement said "The president assures all Nigerians once again that the federal government and national security agencies will continue to intensify ongoing efforts to end Boko Haram's senseless attacks until the terrorists are routed and totally defeated."

The inability of the military to curb attacks has brought international criticism, with the United Nations noting the government is failing in its duty to protect citizens. UN Secretary-General Ban Ki-moon in a statement Monday "reiterates the readiness of the United Nations to support Nigeria as it responds to this challenge in a manner consistent with its international human rights obligations."